Elements

The combination of electrons and protons forming stable atomic structures result in different kinds of elementary substance having specific characteristics. A few examples are the elements hydrogen, oxygen, carbon, copper, and iron. An element is defined as substance that cannot be decomposed any further by chemical action. The atom is the smallest particle of an element that still has the same characteristics as the element. Atom itself is a Greek word meaning a particle too small to be subdivided. As an example of the fact that atoms are to small to be visible, a particle of carbon the size of a pinpoint contains many billions of atoms. The electrons and protons within the atom are even smaller.

Table lists some more examples of elements. These are just a few out of a total of 106. Notice how the elements are grouped. The metals listed across the top row are all good conductors of electricity. Each has an atomic structure with an unstable outside ring that allows many free electrons.

The semiconductors have 4 electrons in the outermost ring. This means they neither gain or lose electrons but share them with similar atoms. The reason is that 4 is exactly halfway to the stable condition of 8 electrons in the outside ring.

The inert gases have a complete outside ring of 8 electrons, which makes them chemically inactive. Remember that 8 electrons in the outside ring is a stable structure. An example is neon.

Read More......

Conductors, Insulators, and Semiconductors

When electrons can move easily from atom to atom in a material, it is a conductor. In general, all the metals are good conductors, with silver the best and copper second. Their atomic structure allows free movement of the outermost orbital electrons. Copper wire is generally used for practical conductors because it costs much less than silver. The purpose of using conductors is to allow electric current to flow with minimum opposition.

The wire conductor is used only as a means of delivering current produced by the voltage source to a device that needs the current in order to function. As an example, a bulb lights only when current is made to low through the filament.

A material with atoms in which the electrons tend to stay in their own orbits is an insulator because it cannot conduct electricity very easily. However, the insulators are able to hold or store electricity better than the conductors. An insulating material, such as glass, plastic, rubber, paper, air, or mica, is also called a dielectric, meaning it can store electric charge.

Insulators can be useful when it is necessary to prevent current flow. In addition, for applications requiring the storage of electric charge, as in capacitors, a dielectric material must be used because a good conductor cannot store any charge.

Carbon can considered a semiconductor, conducting less than the metal conductors but more the insulators. In the same group are germanium and silicon, which are commonly used for transistors and other semiconductor components.

Read More......

Electrons and Protons in the Atom

Although there are many number of posibble methods by which electrons and protons might be grouped, they assemble in specific combinations that result in a stable arrengement. Each stable combination of electrons and protons makes one particular type of atom. Figure 1 illustrates the electron and proton structure of one atom of the gas hydrogen. This atom consists of a central mass called the nucleus and 1 electron outside. The proton in nucleus makes it the massive and stable part of the atom because a proton is 1840 times heavier than electron.

In figure 1, the 1 electron in the hydrogen atom is shown in an orbital ring around the nucleus. In order to account for the electrical stability of atom, we can consider the electron as spinning around the nucleus, as planets revolve around the sun. Then the electrical force attracting the electrons in toward the nucleus is balanced by the mechanical force outward on the rotating electron. As a result, the electron stays in its orbit around the nucleus.

In an atom that has more electrons and protons than hydrogen, all the protons are in the nucleus, while all the electrons are in one or more outside rings. For example, the carbon atom illustrated figure 2a has 6 protons in two outside rings. The total number of electrons in the outside rings must equal the number of protons in the nucleus in a neutral atom.

The distribution of electrons in the orbital rings determines the atom’s electrical stability. Especially important is the number of electrons in the ring farthest from the nucleus. This outermost ring requires 8 electrons for stability, except when there is only one ring, which has a maximum of 2 electrons.

In the carbon atom in fig. 2a, with 6 electrons, there are just 2 electrons in the first ring because 2 is its maximum number. The remaining 4 electrons are in the second ring, which can have a maximum of 8 electrons.



As another example, the copper atom in Fig. 2b has only 1 electron in the last ring, which can include 8 electrons. Therefore, the outside ring of the copper atom is less stable than the outside ring of the carbon atom.

When there are many atoms close together in a copper wire, the outermost orbital electrons are not sure which atoms they belong to. They can migrate easily from ane atom to another at random. Such electrons that can move freely from one atom to the next are often called free electrons. This freedom accounts for the ability of copper to conduct electricity very easily. It is the movement of free electrons that provides electric current in a metal conductor.

The net effect in the wire itself without any applied voltage, however, is zero because of the random motion of the free electrons. When voltage is applied, it forces all the free electrons to move in the same direction to produce electron flow, which is an electric current.

Read More......